Fix `$nginx_upstream_defaults` type
Fix `$nginx_upstream_defaults` type

In my understanding, `$nginx_upstream_defaults` should be of type
`UpstreamDefaults`, not `UpstreamMemberDefaults`.

voxpupuli/puppet-nginx,jfryman/puppet-nginx,jfryman/puppet-nginx,raphink/puppet-nginx,voxpupuli/puppet-nginx